This invention generally relates to slider-operated plastic zippers intended for use in reclosable pouches, bags or other packages. In particular, the invention relates to methods and apparatus for feeding sliders to a slider insertion device.
Reclosable fastener assemblies are useful for sealing thermoplastic pouches or bags. Such fastener assemblies often include a plastic zipper and a slider. Typically, the plastic zippers include a pair of interlockable fastener elements, or profiles, that form a closure. As the slider moves across the profiles, the profiles are opened or closed. The profiles in plastic zippers can take on various configurations, e.g. interlocking rib and groove elements having so-called male and female profiles, interlocking alternating hook-shaped closure elements, etc. Reclosable bags having slider-operated zippers are generally more desirable to consumers than bags having zippers without sliders because the slider eliminates the need for the consumer to align the interlockable zipper profiles before causing those profiles to engage.
Conventional slider-operated zipper assemblies typically comprise a plastic zipper having two interlocking profiles and a slider for opening and closing the zipper. In one type of slider-operated zipper assembly, the slider straddles the zipper and has a separating finger at one end that is inserted between the profiles to force them apart as the slider is moved along the zipper in an opening direction. The other end of the slider is sufficiently narrow to force the profiles into engagement and close the zipper when the slider is moved along the zipper in a closing direction. Other types of slider-operated zipper assemblies avoid the use of a separating finger. For example, U.S. Pat. No. 6,047,450 discloses a zipper comprising a pair of mutually interlockable profiled structures, portions of which form a fulcrum about which the profiled structures may be pivoted out of engagement when lower edges of the bases are forced towards each other.
An improvement in sliders is disclosed in U.S. patent application Ser. No. 10/096,409 filed on Mar. 11, 2002 and entitled xe2x80x9cInsertion Apparatus for Attaching Sliders onto Zipper Bags and Filmxe2x80x9d. This slider can be inserted on the zipper so that the zipper is secured in the slider. As a result, during an opening of the reclosable bag the interlocking closure elements of the zipper will not unintentionally re-engage within the slider. For example, a reengagement of the interlocking closure elements could occur when the zipper opening end of the slider is pushed toward a closed zipper park position. Such a re-engagement can occur during operation of the zipper or if the slider is inserted too far from a slider end stop on the zipper. By reducing the possibility of unintentional re-engagement of the interlocking members of the profiles, production of defective bags is reduced. U.S. patent application Ser. No. 10/096,409 discloses a slider insertion apparatus comprising an activator that opens a first portion of a zipper tape, a pusher that inserts the slider onto a second portion of the zipper tape, and a zipper guide that holds a third portion of the zipper tape closed. The zipper guide and the activator with pusher are manufactured to facilitate forward movement of the zipper tape within the slider insertion apparatus; to properly position the profiles of a section of zipper for slider insertion; and to secure an adjacent section of the zipper when the slider is inserted. A loading rack with a supply of sliders may be part of the slider insertion apparatus, with the loading rack being a mechanically attachable device or module.
Systems for transporting sliders to a slider insertion device are disclosed in U.S. patent application Ser. No. 10/106,687 (incorporated by reference herein) filed on Mar. 25, 2002 and entitled xe2x80x9cSystem for Transporting Sliders for Zipper Bagsxe2x80x9d. That application discloses feeding sliders into a slider insertion device by means of a feeder tube that only accepts correctly oriented sliders having an asymmetric profile, i.e., one leg of the slider is longer than the other leg. Sliders are launched into the feeder tube by a sender apparatus that is controlled by a programmable controller based on feedback received by the controller from various sensors that detect the presence or absence of sliders at particular locations in the slider transport system. The sliders are pneumatically transported in predetermined quantities from a supply of sliders, e.g., a vibratory hopper, to a loading rack.
U.S. patent application Ser. No. 10/106,687 discloses embodiments in which sliders are transported via a flexible feeder tube that connects an exit port of the sending apparatus with an entry port of a loading rack mounted to a slider insertion device or of the slider insertion device itself. In the case where a single feeder tube is used, the length of that tube must be selected as a function of the available layout at a particular plant or facility. The length of feeder tube will need to be at least equal to the distance separating the exit port of the slider sender apparatus and the entry port of the slider insertion apparatus, which in turn will depend on placement of those apparatus. The placement of equipment is a function of the location and configuration of the available space and the presence of obstacles or impediments to the feeder tube being laid in a straight line. These factors will vary from plant to plant, making it necessary to customize the feeder tube length for each installation of slider insertion equipment. In particular, measurements will need to be made at the site of installation before the feeder tube is cut and shipped by the equipment vendor.
Moreover, when the automated slider insertion equipment is moved from one location in a plant to another location in the same plant or to a different plant, a length of feeder tube that was suitable for one layout of the equipment may become unsuitable when that equipment is rearranged at a new site where new specifications must be met. If a shorter feeder tube is needed, then of course the existing feeder tube can be cut, but in the case where re-installation or re-configuration of the slider insertion system mandates a longer feeder tube, the existing short feeder tube may be rendered unusable.
In addition, the labor involved in measuring a site where slider insertion equipment is to be installed, calculating the length of the feeder tube required, and then cutting feeder tubing to the calculated length must increase the cost of the equipment. Further, errors in measurement or prediction could give rise to inefficiencies and economic loss.
There is a need for a feeder tube system that can be easily adapted to suit different manufacturing plant circumstances. In particular, there is a need for a slider feeder tube system in which the overall length of the slider feeder tubing can be varied to fit the requirements of any installation.
The present invention is directed to a modular slider feeder tube system that can be easily assembled to meet any length requirement. This is accomplished by connecting two or more feeder tubes in a chain to form a conduit of sufficient length. The feeder tubes may be cut to one or more predetermined lengths and stored in inventory. For each installation, a predetermined number of feeder tubes can be shipped and then linked together by the installer at the installation site. The feeder tubes are spliced together using tube coupling devices that also form a part of the invention. The invention is further directed to a method for installing a modular feeder tube system to connect a slider sender apparatus to a slider insertion apparatus.
One aspect of the invention is a tube made of resilient material and comprising a channel that extends from a first opening at one end of the tube to a second opening at the other end of the tube, the first opening having a first profile that is asymmetric and the second opening having a second profile different than the first profile, the area of the second profile being greater than the area of the first profile. The channel comprises two sections, a relatively longer channel section running from the first opening to an intermediate point along the tube length and a relatively shorter channel running from the intermediate point to the second opening. The longer channel section has the first profile along its entire length.
Another aspect of the invention is a tube coupling device comprising an elongated body and first and second clamping plates. The elongated body comprises a central section, a first mandrel projecting from one end of the central section, a second mandrel projecting from the other end of the central section, and a channel of constant profile running through the first and second mandrels and the central section. The first and second clamping plates are fastened to opposing sides of the central section. The first clamping plate comprises a first projection directed toward the first mandrel and a second projection directed toward the second mandrel, while the second clamping plate comprises a third projection directed toward the first mandrel and a fourth projection directed toward the second mandrel.
A further aspect of the invention is a modular feeder tube system comprising first and second feeder tubes having respective ends that are coupled by a tube coupling device. Each of the first and second feeder tubes is made of resilient material and comprises a respective channel having a profile that is asymmetric and substantially constant along the lengths of the channels. The tube coupling device also comprises a channel, via which channel the channel of the first feeder tube communicates with the channel of the second feeder tube. Each of the channels maintains the orientation of each slider passing therethrough so that the same end of the slider is always in the lead.
Yet another aspect of the invention is a method of installing a modular feeder tube system to connect a slider sending apparatus to a slider insertion apparatus, comprising the following steps: (a) coupling first through N-th feeder tubes together in a chain, wherein Nxe2x89xa72; (b) coupling an uncoupled end of the first feeder tube to the slider sending apparatus; and (c) coupling an uncoupled end of the N-th feeder tube to the slider insertion apparatus.
A further aspect of the invention is a system comprising: a source of sliders; a slider sender apparatus coupled to receive sliders from the slider source; a modular feeder tube system comprising first through N-th feeder tubes spliced together in a chain, wherein Nxe2x89xa72, one end of the first feeder tube being coupled to the slider sender apparatus; and a slider insertion apparatus coupled to one end of the N-th feeder tube. Each of the slider sender apparatus, first through N-th feeder tubes, and slider insertion apparatus comprises a respective channel, the channels being in communication to form a conduit, each of the channels being profiled to maintain the orientation of each slider passing therethrough so that the same end of the slider is always in the lead.
Other aspects of the invention are disclosed and claimed below.